A refrigeration or HVAC system would typically include a compressor, a condenser, an expansion device, and an evaporator that form a refrigerant circuit. Such a circuit can be embodied in what is known as a chiller.
Chillers for example can be used to cool a process fluid, such as water, where such process fluid can be directly used or may be used for various other cooling purposes, such as for example cooling a space. In a cooling cycle, refrigerant vapor is generally compressed by the compressor, and then condensed to liquid refrigerant in the condenser. The liquid refrigerant can then be directed through the expansion device to reduce a temperature and can become, at least in part, a liquid/vapor refrigerant mixture (two-phase refrigerant mixture). The refrigerant, e.g. including two-phase mixture, is directed into the evaporator to exchange heat with a fluid moving through the evaporator. The refrigerant mixture can be vaporized to refrigerant vapor in the evaporator, and the refrigerant vapor can then be returned to the compressor to repeat the refrigerant cycle.
The refrigerant can enter the evaporator by way of inlet piping into a distributor. When the evaporator is a shell and tube evaporator, the distributor can often reside inside the shell of the evaporator on the shell side, where the shell has an inlet or nozzle to access the distributor using the inlet piping. The distributor has openings so that the refrigerant can be distributed on the shell side of the evaporator and so that the refrigerant can exchange heat with a fluid passing through the inside of the tubes, which is known as the tube side, and where tubes are often constructed as a tube bundle. The fluid, which may be the process fluid such as for example water, can then be cooled in a cooling cycle of the evaporator.
One type of shell and tube evaporator is known as a flooded evaporator, where refrigerant is to enter at a bottom portion of the shell and where, depending on the operating condition of the chiller, tubes of the tube bundle may be wetted by the refrigerant flowing through the evaporator.